Lingenfelter Performance Engineering Turbo System - Vette Tech

An Up-Close Look At Lingenfelter Performance Engineering's 800hp Twin-Turbo System For The Z06

Turbo kits are comparatively rare, when compared with the plethora of supercharger systems on the market. That's because, unlike most bolt-on blowers, which easily can be adapted to a variety of vehicles, turbo kits present unique challenges. There's more to contend with in the routing of inlet and outlet tubing between the exhaust manifolds, turbocharger(s), and engine intake.

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At a minimum, major changes are required of the exhaust system. Of course, all that plumbing changes for a different vehicle, whereas adapting a Roots blower, for example, requires comparatively minor revisions to suit the accessory drive and intercooler mounting.

To put it simply, turbo kits are expensive to engineer and produce, but many enthusiasts prefer the higher-rpm application of power, the adjustability of the performance, and the on-demand power that doesn't compromise daily driving characteristics. Often, enthusiasts must rely on custom-designed systems-and hope the shop they've entrusted their car with knows what it's doing.

Decatur, Indiana-based Lingenfelter Per-formance Engineering's (LPE) solution to turbo systems is a hybrid of sorts, which blends the attributes of a fully engineered kit with the precision fitment of a custom system. The company has designed Corvette-specific kits, but it fits them individually to each vehicle for a more accurate and precise installation-much like a custom-tailored suit versus a "close enough" off-the-rack one. LPE also rebuilds the engine to make it boost-friendly, including forged-aluminum, lower-compression pistons and an upgraded rotating assembly.

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"There are enough vehicle-to-vehicle variances that we feel our method is the best at ensuring the best installation and a more robust engine," says LPE's Jeff Myers. "And typically one of the side benefits is, most customers report better fuel economy in normal everyday driving."

We recently visited LPE's shop to follow the installation of the company's twin-turbo system on a C6 Z06. In fact, it was the blue Specter Werkes/Sports GTR Z06 that wowed SEMA attendees last fall and was previewed in VETTE earlier this year. With the 505hp LS7 as the foundation, LPE rates the system at a stunning 800 hp. Notably, the kit sacrifices nothing in driveability, such as air conditioning, power amenities, and the like.

LPE's system uses a pair of medium-size Garrett ball-bearing turbos and an air-to-air intercooler. The turbos are mounted low in the engine compartment, which helps minimize underhood heat. The mid-size hairdryers also offer an optimum combination of tremendous airflow and minimal lag. In fact, lag is, for all intents and purposes, nonexistent here. The turbos spool quickly and deliver a smooth yet incredibly forceful application of power.

Although boost in any turbo system is tunable, the base LPE system delivers about 10-12 pounds to help the 7.0-liter engine produce 800 horses. The turbo system isn't installed until after the rebuilt engine is lowered into place. We should note, too, that our photos provide an overview of the installation. There are far more details than we have room to show, but what we've shown here provides an excellent glimpse into the major components and procedures involved.

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The turbo installation takes place on a Specter Werkes/Sports GTR built around a Corvette Z06. All of the mechanical work was performed at Lingenfelter Performance Engineering's Indiana facility.

LPE removes the Z06's LS7 engine and rebuilds it to suit the demands of turbo-charging. That includes a short-block with a new, forged-steel crankshaft, forged-steel connecting rods, and lower-compression 9.0:1 pistons. The heads also receive high-temperature-resistant Inconel exhaust valves.

The turbo system is designed to mount the turbochargers directly to custom, heavy-duty exhaust manifolds. In the low-slung Corvette chassis, that still puts them at the bottom of the engine compartment, which helps keep heat farther away from the engine and air intake system.

One of the other pre-installation procedures involves prepping the engine for the oiling requirements of the turbos. That involves swapping the stock oil cooler for an aftermarket model, fitting a scavenge pump to pull returned oil from the low-mounted turbos, and adding a feed line (seen here) that sends the circulated oil back to the pan.

The system's installation starts with bolting on the exhaust manifolds. With the hood removed and the considerable chassis clearance on the Corvette, it's easy to do from the top of the engine compartment.

With the exhaust manifolds and their oxygen sensors in place, the first turbocharger is hoisted into position on the passenger side, sliding onto the mounting studs protruding from the exhaust manifold's mounting flange.

LPE uses many hard lines in the system, including the oil-feed and return lines at the turbo, which require custom fitting to account for the slight variances among vehicles. After the first turbo was installed, for example, this line was measured and cut to fit the oil-feed line to it.

The hard oil-feed line wraps under the oil pan and up to a T-junction in an aftermarket oil cooler. The bottom fitting is reserved for the driver-side turbo's feed line.

The installed oil-feed line is seen routing away from the turbo and along the oil-pan rail. Installing the line at this point in the project is necessary, because access to it would be almost impossible after the down tube and other sections of the system are installed.

LPE's basic system uses a pair of these mid-size Garrett GT30-series water-cooled, oil-fed ball-bearing turbochargers and Forge actuators. The medium-size bodies of the turbos make them ideal for easier fitment and quick spool-up.

A thick, 3/4-inch flange is attached to the exhaust manifold, where the turbocharger mounts. This is necessary to prevent warping under the extreme temperatures generated when the system produces maximum boost. Also note the heat shield attached to the manifold.

With the passenger-side turbo and its oil-feed line in place, the driver-side turbo is installed and its line attached.

A scavenge system draws oil cycled through the turbochargers back into the engine's oiling system. Because the turbos are mounted low, gravity is not sufficient for draining to the oil pan, so Lingfelter designed a small tank that collects the return oil from the turbos and, with the help of a mechanical pump, draws it out and back into the pan.

The turbochargers are also water cooled, which requires tapping into the vehicle's cooling system for feed and return. Inserting a junction in the heater hoses does the trick. As seen here, it's double-clamped on both ends to ensure a leak- and blow-proof seal.

Like the oil lines, the water lines to and from the turbos are hard. They're routed around the oil pan, like the oil lines. This configuration is more time consuming to fabricate and install, but if the lines were simply run directly under the pan, they'd be susceptible to damage. To make installation easier in the tight confines on the bottom of the engine compartment, banjo-type fittings are used to connect the coolant system to the turbos.

Next, the down tubes-the pipes that connect the exhaust outlet of the turbos to the vehicle's exhaust system-are installed, but not before they're test-fitted to ensure there aren't interference issues with any of the other turbo-system or chassis components.

Although a metal gasket is used between the turbos and exhaust manifolds, the down pipes are mated to the turbos with Permatex Ultra Copper high-temperature silicone gasket mer. It's spread liberally on the mounting flange.

The custom oil-scavenge tank also mounts to the bellhousing. The hard lines feeding the tank carry gravity-fed oil from the turbos, while the large flexible hose draws out the oil with vacuum from a pump mounted at the front of the engine. The oil is then reintroduced to the engine-oil circuit.

The custom oil-scavenge tank also mounts to the bellhousing. The hard lines feeding the tank carry gravity-fed oil from the turbos, while the large flexible hose draws out the oil with vacuum from a pump mounted at the front of the engine. The oil is then reintroduced to the engine-oil circuit.

LPE uses flexible silicone hoses for the air-intake tubes and the discharge tubes that feed the boosted air charge to the intercooler. They're carefully routed from the turbos along the chassis rails, with numerous checks and inspections to ensure they don't bind or interfere with the suspension and steering systems.

Like other aspects of the installation, the intake Y-pipe is custom-fitted to each vehicle. After that, the heat exchanger and intake tube are painted black. The intake feeds the stock, 90mm throttle body, but LPE modifies it slightly to increase airflow.

When the intake tubes are routed and securely attached, the project moves into the final stages, with buttoning up a myriad of details, including installing the mass air sensor (seen here), reconnecting the fuel system, and performing a number of wiring duties.

Fuel-system upgrades are necessary for an engine producing about 300 more horses than stock. To that end, LPE installs a set of 60-lb/hr injectors and supports them with a Kenne Bell Boost-A-Pump fuel-pump-voltage amplifier.

The completed installation gives this Z06-based GTR an 800hp reinforcement for its racetrack-derived styling. More accurately, it put down 625 hp at the tires on Lingen-felter's chassis dyno, or about 820 at the flywheel. We're planning a full feature on the car as soon as possible.

The final major task in the project involves reinstalling the exhaust system. As is the case with most turbo installs, a modified exhaust system is required. Much of it is based on Corsa components, but with some custom-fabricated parts also included.

An interesting detail on this system is the reuse of the vacuum port that once actuated the factory two-stage exhaust system. It's now used to actuate a fuel-pressure regulator mounted at the rear of the vehicle, near the fuel tank.